Leyland Cypress & Snake Oil Salespeople

 In Tree Pest News


A living fence can make an excellent privacy screen around the property. As long as it does its job blocking undesirable sights, reduces annoying sounds, doesn’t encroach upon the neighbors, stays upright during storms, and remains green year around, it mostly goes unnoticed. But when orange or brown leaves start appearing (called  flagging), it gets our attention.

This spring we’ve been deluged with distress calls from homeowners and H.O.A.’s, whose Leyland cypress are browning. While Leylands are evergreen, fast-growing & have the potential to make an excellent privacy fence (some unknown place on the planet), here in the South, they are often riddled with several pests (some known to walk upright upon two legs).

Some of the more common pests are Phytophthora root rot, Botryospaeria canker, Passalora needle blight, bagworms, spruce spider mites, juniper scale, and the worst offender; Seiridium canker (Seiridium unicorne), for which, there is NO CURE (though cultural methods may slow, if not temporarily halt the disease)!

While close planting, urban stresses & environmental conditions (such as drought & spring frost damage), are the breeding ground for Seiridium canker, panicky, uninformed homeowners seem to attract snake oil salesmen. Years ago, the traveling medicine show only stuck around long enough to peddle their wares. By the time you woke up reeling the next morning & realized you’ve been had, only the tracks of their wagon wheels remained.

Today’s snake oil salesman drives a company truck, dresses in embroidered uniforms, comes licensed & certified, and has no intention of leaving town. The typical call we receive usually goes something like this: “I spent a thousands of dollars on my trees last year & they have only gotten worse. This year the same company wants to repeat the treatment. What should I do?”

Because the salesman seems knowledgeable and is persuasive, and owner can’t bear the thought of loosing their trees, many owners feel compelled to continue the madness (like a moth to the flame). Albert Einstein once said, “Insanity (is) doing the same thing over & over again & expecting different results.” Some companies have made out like bandits providing “soil conditioning.” Get another opinion. Get several!

Besides the pests we’ve already listed, there are other considerations when managing Leylands. Are they planted too deeply? Are they girdled? Have the roots become established? Are they planted too close together? Are they growing into taller shade trees? Do they have multiple trunks? Are they encroaching upon the neighbors? Are they properly mulched? Are they properly watered? Do they have good drainage? How long will I live here?

The way out of this mindless maze is to become informed. Find out all you can (start online with this site: http://www.clemson.edu/extension/hgic/pests/plant_pests/trees/hgic2004.html). Consider hiring an independent consulting arborist (some one that doesn’t stand to gain by their own advice).

If you hire a contractor, insist he take samples to be analyzed by an independent lab (such as a state forestry or university extension office) before you hire. Have the results e-mailed to you and/or included in his detailed proposal. Have him monitor your plants periodically, and report changes to you. Through ground inspections & digital photos, let him prove to you that you have spent wisely before you spend more.

Rather than becoming overwhelmed by the problem, take charge of your yard! Here are some cultural practices that we have seen work in dealing with Seiridium canker (as well as other diseases):

(1) Prune dead leaves & branches, and remove from the property. Sterilizing pruning tools between each cut is usually impractical. As long as the tree is dry, disease transmission will be limited.

(2) Consider removing every other tree if they are planted less than 12 feet apart.

(3) Consider removing other trees & structures that cause encroachment/shading.

(4) Don’t hesitate removing a tree that has more brown/orange than green. Not only is there little hope of saving it, but it can spread disease to other trees. Usually, the canker will work its way through a row of trees.

(5) Never top or severally prune (though crown reduction may be necessary with encroachment).

(6) Irrigate (very important) at least 1 full inch of water within the dripline once a week in the early morning during drought & insufficient rainfall (especially June thru October). Overhead sprinklers work better than soaker hoses, but make sure they cover the entire critical root zone & do not spray up into the leaves/crown & spread the disease (you may have to prune the bottom branches away; this will improve their health). Well irrigated Leylands can outgrow the canker. Make sure you have good drainage.

(7) Mulch 1 to 2 inches, aged, all-tree mulch out to the dripline.

(8) Don’t over-fertilize. Lay off the nitrogen. Organic slow release is OK in moderation.

(9) Green giant arborvitae is a good replacement tree. Make sure you properly identify & choose a healthy, single-trunk specimen (see our Tree Selection Guide http://greentreedoctor.com/selection). But remember, green giants can also grow over 100 in height.

(10) Should you decide to start over (if your trees are too diseased, and/or have multiple trunks that are failing), choose better next time. Consider planting a pest-free, broad-leaf evergreen, such as Nellie R. Stevens holly or tea olive (we can assist you in selection).

(11) Consider installing 3 different species & stagger the rows. This will look more natural (like a garden or forest), and should a new disease take out one species, you’ll have the remaining two. If you choose the right plants, and plant properly, you’ll have many years of enjoyment with little or no maintenance.

(12) If it’s going to cost too much to have your trees removed (either every other tree or the whole lot), consider having them removed in January or February when tree services are hungry for work (and are willing to work cheaper).

(13) Finally, don’t panic. It probably looks worse than what it actually is. And even if it is that bad, diseased trees can continue to perform a screening function until you are able to prune or remove them. What seems to be such a horrible eyesore to you, likely goes unnoticed by the neighbors.

(14) If, after all these instructions and assurances, you still need help, please contact us.  We can provide independent consultation for a nominal fee, go through the best management practices, and steer you towards tree care companies that won’t take advantage of you.

(15) Our cultural recommendations may not be the silver bullet that some companies claim, but they can and do work. Below is an example of Leylands that notably improved during this period (Easley, SC, Fire Department).


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